F# Get Members of Module

Question

Given

type Unit = {
            Name : string
            Abbreviation : string
            Value : float
        }

module Lets =
    let meter = { Name = "meter"; Abbreviation = "m"; Value = 1.0 }
    let millimeter = { Name = "millimeter"; Abbreviation = "mm"; Value = 1e-3 }

How can I create a function with this signature?

let units () : Units[] = ...

Answer 1

F# Modules are just static classes when compiled.

Using reflection you should be able to grab these values with something like this:

module Lets =
    type Dummy = | Dummy
    let meter = { Name = "meter"; Abbreviation = "m"; Value = 1.0 }
    let millimeter = { Name = "millimeter"; Abbreviation = "mm"; Value = 1e-3 }


let t = typeof<Lets.Dummy>.DeclaringType
t.GetProperties() |> Array.map(fun p -> p.GetValue(null, null) :?> Unit)

It's tricky to get the type of the module, but that trick will do it for you.

EDIT:

Updated to cast directly to Unit . The cast as shown is unsafe, and will throw if GetValue does not return a Unit type.

Additionally unit is a type in F#, it might be clearer to use a different name.